How can I automatically relaunch nautilus if I quit the program?

#!/bin/bash

# NAME: ttlus (Twenty Thousand Loops Under Startup)
# PATH: $HOME/askubuntu/
# DESC: Answer for: https://askubuntu.com/questions/1180043/how-can-i-automatically-relaunch-nautilus-if-i-quit-the-program
#       Call Nautilus, named after Twenty Thousand Leagues Under the Sea novel,
#       20,000 times in loop from Startup Applications
# DATE: October 10, 2019.  Modified October 16, 2019.

# NOTE: Things that don't work:
#       https://askubuntu.com/questions/965052/how-to-make-script-wait-for-nautilus-to-exit
#       https://ubuntuforums.org/showthread.php?t=1604843

# UPDT: Rpelace loop with occassional focus grabbing and unpredictable delays:
#    while ps -L -p "$PID" -o pid,nice,lwp,comm | grep pool > /dev/null ; do
#       with:
#    while gdbus introspect --session --dest org.gnome.Nautilus \ ... 3 lines

LoopLimit=20000
Program="nautilus"
#Program="/usr/bin/nautilus --gapplication-service"
PID=$(pgrep nautilus)
Sec=3

if [[ $PID == "" ]] ; then
    notify-send "ERROR in $0: Cannot find nautilus PID"
    exit
fi

for (( l=0; l<LoopLimit; l++ )) ; do
    # Is nautilus file manager running? 1 Window only is desktop icons
    while gdbus introspect --session --dest org.gnome.Nautilus \
        --object-path /org/gnome/Nautilus --recurse | \
        grep -q '^ *node /org/gnome/Nautilus/window/' | \
        grep -v '/window/1' ; do
            sleep "$Sec"
    done
    "$Program" "$HOME" 2> /dev/null
    sleep $(( Sec / 2 ))
done

notify-send "ERROR in $0: $Program exceeded $LoopLimit loop limit"